A170910 Write exp(-x) = Product_{n>=1} (1 + g_n * x^n); a(n) = numerator(g_n).

-1, 1, 1, 3, 1, 13, 1, 27, 8, 91, 1, 1213, 1, 505, 1919, 2955, 1, 24557, 1, 1136313, 34943, 12277, 1, 65978519, 624, 57331, 58528, 195948483, 1, 1052424027703, 1, 77010795, 7085759, 1179631, 37497599, 7047825380633, 1, 5242861, 89281919, 355723139681937

Offset

1,4

Links

Table of n, a(n) for n=1..40.

H. Gingold, H. W. Gould, and Michael E. Mays, Power Product Expansions, Utilitas Mathematica 34 (1988), 143-161.

G. Helms, A dream of a (number-) sequence

Example

-1, 1/2, 1/3, 3/8, 1/5, 13/72, 1/7, 27/128, 8/81, 91/800, 1/11, ...

Maple

L:=100; t1:=exp(-x); t0:=series(t1, x, L): g:=[]; M:=40; t2:=t0:
for n from 1 to M do t3:=coeff(t2, x, n); t2:=series(t2/(1+t3*x^n), x, L); g:=[op(g), t3]; od: g;

Crossrefs

Cf. A170911 (denominators).

Sequence in context: A263008 A016479 A248843 * A134768 A295827 A277197

Adjacent sequences: A170907 A170908 A170909 * A170911 A170912 A170913

Keyword

sign,frac

Author

N. J. A. Sloane, Jan 30 2010

Status

approved